Various alkali metal acetylides have been described in the literature, and various procedures for preparing such acetylides have been suggested. U.S. Pat. No. 3,303,225 describes a procedure for preparing alkali metal acetylides containing more than one alkali metal atom per molecule. In particular, the polymetalated acetylenes are prepared by reacting an organoalkali metal compound with an acetylene under conditions to effect step-wise replacement of, first, the acetylenic hydrogen atom and, second, the hydrogen atoms attached to the carbon atom which is alpha to the acetylenic linkage. The patentees indicate that the metalated 1-acetylenes are active as polymerization initiators for vinylidene-containing monomers.
The metalation of 1-butyne with excess n-butyllithium is discussed by Eberly and Adams in J. Organometal. Chem., 3(1965) 165-167. The authors report that two moles of n-butyllithium react with one mole of 1-butyne to yield a hexane-insoluble 3-methylpropynylene-1,3-dilithium. Three moles of n-butyllithium are reported to react with one mole of 1-butyne to yield a hexane-insoluble 3-methylpropynylenedilithium n-butyllithium adduct.
The stereopolymerization of butadiene and styrene in the presence of acetylenes and ketones is described by H. E. Adams et al, in Kautschuk und Gummi. Kunststoffe 18. Jahrgang, pp. 709-716, Nr, 11/1965. The authors studied the reaction of 1-butyne with 1, 2 and 3 moles of n-butyllithium in hexane, and the use of the materials obtained from such reactions as catalysts. The reaction of 1-butyne with one mole of n-butyllithium resulted in the formation of a white precipitate where the acetylenic hydrogen was replaced by lithium. When a second mole of n-butyllithium was added slowly to the reaction mixture, the white precipitate dissolves and the product is a clear lemon-yellow solution. Upon standing at room temperature, the solution becomes cloudy, and after about 210 hours, the precipitation of a yellow solid is complete. The product was identified as 1,3-dilithio-1-butyne. When an excess of n-butyllithium is added to the precipitate of 1,3-dilithio-1-butyne, the precipitate dissolves to form a golden-yellow solution. There were signs of precipitation after two weeks, and after two months, a copius precipitate had formed. The precipitate is identified as a complex of 1,3-dilithio-1-butyne and n-butyllithium.
The use of dilithium salts in the polymerization of butadiene is reported by Makowski et al, J. Macromol. Sci.--Chem., E2(4) pp. 683-700, July, 1968. Among the lithium compounds studied were the 1,3-dilithioacetylides such as the compounds obtained by reacting 1-hexyne with n-butyllithium in ratios of 0.5 and 0.67. At a ratio of 0.5, homogeneous catalyst solutions in hydrocarbons were obtained. Above this ratio, some precipitate was present. In all cases, however, polymerization with butadiene resulted in low molecular weight polymer solutions. That is, where the catalyst solution included precipitated solids, the solids dissolved during the course of the polymerization. At the ratio of 0.5, the polymer solution was very viscous, and at the ratio of 0.67 a gelled solution resulted. However, when Attapulgus clay was added to the viscous solution or to the gelled solution, fluid solutions were obtained. This result was attributed to the presence of water in the clay.
Masuda et al, Macromolecules, Vol. 20, No. 7, (1987) pp 1467-1487 describe the preparation of poly[3-(trimethylsily)-1-alkynes]. The monomeric 3-(trimethylsilyl)-1-alkynes are prepared by reacting a 1-alkyne with n-butyllithium to prepare the 1,3-dilithiated intermediate which is then reacted with chlorotrimethylsilane to form the desired monomer.
Polylithium polymerization initiators also are described in U.S. Pat. No. 3,377,404. The initiators are prepared by first contacting an excess of lithium with an organic halide containing two to four halogen atoms in a polar solvent such as ether. The intermediate formed in the this step can be represented by the formula EQU RLi.sub.x
wherein x is an integer of two to four and R is a hydrocarbon group. In a second step, the intermediate is contacted with a small amount of a conjugated diene such as 1,3-butadiene. The amount of diene is generally from about one to about ten moles per mole of lithium compound. After the intermediate has been treated in this manner, a substantial portion or all of the polar solvent is removed and replaced by a hydrocarbon diluent. The polylithiated hydrocarbon soluble compounds prepared in this manner are reported to be useful as initiators of the polymerization of conjugated dienes.
U.S. Pat. No. 3,784,637 describes multi-functional polymerization initiators prepared from polyvinylsilane compounds or polyvinylphosphine compounds. More particularly, the multi-functional polymerization initiators are prepared by reacting an organomonolithium compound such as n-butyllithium with a polyvinyl phosphine compound or polyvinylsilane compound. Preferably, the reaction is conducted in the presence of a solublizing monomer such as a polymerizeable conjugated diene, monovinyl-substituted aromatic compound, or mixtures thereof. Examples of solublizing monomers include conjugated dienes such as 1,3-butadiene and aromatic vinyl compounds such as styrene.